1. Field of the Invention
The present invention relates to a droplet ejection head and a droplet ejection apparatus.
Priority is claimed on Japanese Patent Application No. 2004-305521, filed Oct. 20, 2004, the content of which is incorporated herein by reference.
2. Description of Related Art
Inkjet printers are known as printers that can provide high speed printing with a high image quality. Inkjet printers are equipped with an inkjet recording head that is provided with a cavity (i.e., a pressure generating chamber) having a changeable internal volume. Inkjet printers perform a printing operation by ejecting ink droplets from nozzles in the head while the head is being scanned. Conventionally, ceramic piezoelectric elements represented by PZT (Pb(ZrxTi1-x)O3) are used as head actuators in this type of inkjet recording head. These piezoelectric elements are driven by a drive IC that is mounted on the head. This drive IC may be fixed, for example, onto a bonding substrate that is bonded to one surface side of a flow path forming substrate where the cavity is formed, and is electrically connected by wire bonding or the like to the respective piezoelectric elements (see Unexamined Patent Application, First Publication Nos. 2004-148813, 2003-182076, and 2004-34293).
However, even faster speeds and higher image quality are being demanded in inkjet printers. One technique that cannot be overlooked in order to respond to these demands is to increase the density of the nozzles in the inkjet recording head. Because of this, it is accordingly necessary to achieve higher density packaging and size reductions for the drive IC that drives the piezoelectric elements. However, because wire bonding is employed in current inkjet recording heads, problems occur if such size reductions and higher density packaging are pursued such as short-circuiting occurring due to contact between wires, and a fall in the production efficiency being generated. Namely, by miniaturizing the terminals, a reduction in the size of the drive IC, an increase in the yield from a wafer, and a lowering of costs become possible, however, because of the aforementioned problems, there is a limit of approximately 60 μm to the pitch of the wire bonding, and this will not be able to be overcome in future.
Note that such problems apply not only to inkjet recording heads that eject printing ink, but also apply to droplet ejection heads that eject a liquid other than ink. For example, these problems also occur in droplet ejection heads that are used when a functional film (i.e., metal wiring or the like) is formed by ejecting a liquid that contains a functional material such as fine metal particles onto a substrate, and then drying and baking the substrate.